BLACK_IERAX

Well if any computer does not work due to a hardware failure you will need a technician to fix it as your ex wife did. If you can not access it due to hardware failure you would need to either have spare parts to replace them. Linux is a operating system as is mac os or windows. If you want to troubleshoot it yourself and have the technical experience then yes you will need to have a second machine to have the other running. As for your network card experienced my self a issue that windows updates just made my pc malfunction. On Linux everything was working fine.
Dell has machines that come with Linux Installed out of the box as has the Dell XPS 13 Developer Edition . As for the warranty Usually computers that are targeted for business come with a on site repair. It is usually marketed that way and not all computers have that warranty.
Ok the back up part made me laugh. I'm pretty sure you have no idea how Linux works on this point. Not only do you have graphical backups and strong terminal backup solutions that can take a backup from your hard drive bit by bit. You can reinstall the operating system while keeping your home directory intact. Which in other words means even if you screw up badly you can restore the operating system while keeping your files intact.
Hardware issues are dealt with the same way as every other computer out there. Blue screens usually are a sign that your ram in failing and Linux gives you the option to run memtest upon boot in the grub menu. But in windows Viruses or "malfunctioning" software can also cause BSOD.
P.S. Please respect my initial statement on not quoting me.